Cold stress is one of the most important environmental stresses that can affect temperate and especially tropical plants during vegetative and reproductive stages. When the plant is exposed to the cold stress and senses it, it transmits its message at the cellular level through molecules such as calcium ion and causes a series of changes in the expression of different genes. When the cold stress initially begins as chilling, the plant can respond to this stress by changing the gene expression, producing compatible solutes, producing antioxidant enzymes, producing cold shock proteins, changing the composition of the membrane, etc., which eventually ameliorates the adverse effects of stress on plant growth and development. In this chapter, the abovementioned mechanisms and some other issues will be discussed in further details.
